I'm using this testing a post request on the api tester and it return a 400 bad request.
{
"lists":[{"id": "1712653224"}],
"email_addresses":[{"email_address":"janedoe@doe.com"}],
"last_name":"Doe","first_name":"Jane"}
Hello @MartinC966,
Thank you for reaching out to Constant Contact's API Support.
If you are making a POST then the JSON data format is correct and I would look in to either your header information or how you have your endpoint URL formatted.